The present invention relates to friction materials utilized for wet brake, wet clutch, power shift clutch, power take-off clutch, transmission, etc. for industrial machine vehicles, construction machine vehicles and cars, which are excellent in the wear resistance particularly under the conditions of high-speed and high-pressure applied and in moisture-containing oil.
With conventional paper-like friction materials for operating in oil, the wear is significant under the conditions of high-speed and high-pressure applied and further chipping and peeling-off generate on braking, hence the limit of use conditions has been at low level. Moreover, even if they may be used without problems in a new oil at the beginning of use, a phenomenon of abnormally increased wear occurs when moisture is incorporated into oil due to some external reason, formation of dew, or the like.
As a result of extensive investigations in view of this situation, friction materials for operating in oil having excellent wear resistance under the conditions of high-speed and high-pressure applied and in moisture-containing oil have been developed by the invention.